An online advertisement placement generally refers to a specific advertisement slot on a web page. A collection of multiple advertisement placements is typically referred to as inventory. Advertisement placements are increasingly being filled through a real-time bidding (RTB) exchange, such as ADX®, ADMELD®, PUBMATIC®, and RUBICON PROJECT®. An advertisement placement becomes available when a user/Internet surfer visits a web page where a publisher is selling the advertisement placement on an RTB exchange. The RTB exchange provides a bid request that represents the advertisement placement. A bidding server that has computer hardware linked to the RTB exchange, receives the bid request and responds with either a bid or a decline within a short period of time (e.g., around 50-100 ms or less). If the bidding server wins the bid, the bidding server purchases an advertisement impression, i.e., an instance of an advertisement appearing on the web page.